Cyanine dyes



Patented Mar. 6, 1951 UNITED STATES PATENT OFFICE 2,544,323, CYANINE DYES No Drawing, Original application May 17, 1940,

Serial: No. 335,854,

Divided and this application March 28,1950, Serial No. 152,504. In Great Britain April 24, 1939 12 Claims. (01. amen-40 4) This application is a division of our application Serial No. 335,354, filed May 11, 194.0, which latter application. is continuationrin-part,.oi application Sen No. 331,6 k filed On April 231i 1940, now abandoned. v

o The present invention relates to dyes, belon ,in to, the class. of methineand polymethine dyes and. dyes of similar structure and more particularly to dyes which are useful as sensitizers for photographic silver halide emulsions. These dyes are widely employed in the art of photography and color photography and a great number of cyanine dyes, isocyanine dyes, pseudocyanine dyes, carbocyanine dyes and polymethine dyes having longer methine chains are already known. These dyes are quaternary salts derived from cyclic ammonium bases in which there isa pentavalent nitrogen atom single bound to one neighbour n ring atom'and double bound to the other neighbouring ring, atom of a hetero-cyclic ring whilst the fourth valency of the same ni gen. at m i linked to a hydrocarbon radicahthe fifth valency of the nitrogen atom being in iono'gene linkage with an anion. v

The present invention relatesto the manuiao ture of. methine dyes and, polymethine dyes in which the heterocyclic, ring includes both a nitrogen atom and another hetero-atom such as sulphur and in which the fourth valency of the nitrogen atom is linked not to an. aliphatic. but to. a cyclic carbon atom and tophotographic silver h de m l ns se itized wi h. such. dye or dyes- Whereasthe. form a o is sit'i ns dyes hare e raref e v s me m s brq d enoush to i clude a yclic subst t a the ni rosenat m it do s notv appear that thosedyes and more particularly sensitizing thiazoledyes carrying such, substitunts h v ee Pr pa ed r us n htns tive e uls h 1W b prepared by t at n Ni-ary ated qu tc n'err, s lts Q a het oc i nitrogen base, the ring atomolf which includes another hetero atom such assulphur and which ee e a me h l we n ho e it wtm i cyclic nitrogen atom (or the corresponding methylene bases) by the methods known to be capable of converting hetero-cyclic nitrogen bases containing a reactive methyl group in aposition to acyclic nitrogen atom (or the corre sponding' methylene bases) into dyes of the following general formula:

U H(C4+ HiMfier Ril R X y in which the hydrogen atoms may be. substituted; In the above formula: .I

A is a e eraaterhjother han a nitrogen atom in an atorn chai of a ring system; R1 is a hydrocarbon radical;

X is an anion;

n is zero and m is aerql, 2, or 3, or n and m are 1;

R2 is a hydrocarbon radical;

R3 is a hydrocarbon radical, an atom chain including three atoms which close a 5-membered hetero ring with a carbon atom of the chain of carbon atoms between the two nitrogen atoms, or an atom chain including two or four atoms which close a G-membered hetero ring with a carbon atom of the chain of carbon atoms between the two nitrogen atoms, so as to form a dye having two hetero-cyclic nitrogen compounds. linked by an odd number or carbon atoms. The general form l may als be revresented in. its. tautomeric form:

In the following examples, some of the known methods for producing dyes of the above general formula are applied to the treatment of the N- arylated quaternary salts, the term N-arylated quaternary salts being intended to include also compounds in which cyclic radicals other than aromatic aryl radicals are linked to the nitrogen atom- Q o Example 1 .-o1 gram of 2.4-dimethyl-3-phenylthiazoliui'n iodide (prepared according to the Journal of the American Chemical Society, 1935, page 1381', or to Berichte der Deut'schen Chemischen Gesellschaft, vol. 69/1, page 221) and .5 grm. of p-dimethylaminobenzaldehyde are dissolved by warming in '7 cos. of ethyl alcohol. .17 grm. of piperidine is then added, and the mixture is refluxed for an hour.

After cooling, ether is added, and thereupon an orange-red dye separates out, which is dissolved by heating in a little ethyl alcohol. On cooling this solution, crystals with greenish lustre are formed. The dye, dissolved in water with the addition of a small quantity of methyl alcohol has an absorption maximum at about 485 l. Its formula is probably that of the Z-dimethylaminostyryl-3-phenyl-4-methyl-thiaz01ium iodide:

. H3 max 2 CH (LE4 2 -CH=CHON\ A silver halide emulsion layer is sensitized to green light by the addition of the dye and then shows a maximum of sensitivity at about 450 and another maximum at;about 5510 Example 2.--3 grms. of the 2.4-dimethyl-N- phenyl-thiazolium iodide are heated with 3 grms. of N-methyl-a-thioquinolone-methyl-iodide and 30 cos. of dry pyridine in an oil bath atl20 C. for 1 /2 hours. The addition of waterto the cooled mixture results in the precipitation of a dye, having an absorption maximum in aymethyl alco- 1 holic solution at about 482 l. vIts formula is probably that of the 1'-methyl-3-phenyl-4- methyl-thiazole-pseudo-cyanine iodide:

Example 3.3 grms. of the 2.4-dimethyl-3- phenyl-thiazolium iodide and 40 cos. of dry pyridine are refluxed 1% hours together with 5 cos. ethyl-ortho-acetate. The addition of ether causes the precipitation of a magenta dye, crystallizable from ethyl alcohol, and having in methyl alcoholic solution an absorption maximum at about 548 Its formula is probably that of the 3.3-diphenyl-4.4-7-tri methyl thiazolo-carbo cyanine iodide:

CHi.C\N/

Example 4.4 cos. of dry pyridine, .3 grm. of 2.4-dimethyl-3-phenyl-thiazolium iodide and .5 cc. of ortho-formic acid ethyl ester are heated at about 120 C. for about two hours.- A magenta dye is obtained which can be precipitated from the solution by the addition of ether, The dye 4 is probably the 3.3'-diphenyl-4.4'-dimethylthiazolo-carbocyanine iodide of the formula:

' with 3 cos. orthoformic acid ethyl ester for about 45 minutes; after the addition of ether the solution is allowed to stand for several hours, preferably at 0 C. The liquid is decanted and the residue dissolved in methanol and precipitated again with ether. This may be done several times, whereafter the product is boiled with water and filtered. Green crystals of a metallic lustre are obtained, which are believed to be the 3.3-

di-(p-chloro-phenyl) 4.4 dimethylthiaz olm carbocyanine toluene-sulphonate of the formula ii-( 1 5 r d o-n' CHa-C (g-CH=C'HCH=C CHa Absorption in methylalcoholic solution ca. 560 (max.)

Example 6.--In the foregoing examples the thiazol ring or rings in the resulting dyes are of the simple thiazole type void of ortho condensed rings. A benzothiazolium cyanine dye may be prepared as follows: 12.5 grms. acetyl-diphenylamine are dissolved in 50 cos. pyridine, 6 grms. phosphorus pentasulphide are added and the whole is stirred for 12 hours at C. The upper light yellow layer is decanted oil and the thioamide contained therein is precipitated with hydrochloric acid, filtered ofi by suction and re-' crystallized from alcohol. The compound which has a melting point of 112 C. is identical with the thioacetyl diphenylamine prepared by Bernthsen from carbon disulphide and diphenyl acetamidine (Annalen der Chemie, vol. 192, page 39).

. 6 8 grms. of the thioacetyl diphenylamine (N,N diphenylthioacetamide) thus obtained are dis solved in 30 cos. chloroform and a solution of 4.8 grms. bromine in 10 ccs. chloroform is added in drops, the whole being cooled during this operation. The light yellow color of the solution changes to a dark brown and meanwhile hydrobromic acid is formed. After the mixture has been allowed to stand for two hours the chloroform is distilled off. The base is dissolved in acetone, freed of an undissolved grey powder by filtering off this by-product; and the acetone is evaporated. A brown oil remains and this is dis essee-ace cos. triethyl-ortho-formate are added whole-is lrefluxed' for minutes. --AI-terf o c i-uifthm ether are added, the solution is kept in icej'wate'r for about12 hours and then the precipitated dye is filtered off andwashed with ether. It is believed to be- 2.2'-dipheny1- thio-carbocy'anine acetate and the reaction is believed to proceed as follows:

The dye is purifiedby being dissolved in methyl alcohol and isthereafter converted'intothe iodide by the addition of a warm 10% potassium iodide solution. The formula of the final dye, whose solution in methyl alcohol shows a maximum absorptionat about-565w is believed to be 3.3-

dighenyledibenzo thiazolo carbocyanine-iodide of the formula:

As will be seen from the above formulae the nitrogen atom in at least one of the heterocyclic rings of the dye molecule is linked to a phenyl group. By the use of appropriate starting materials, such as the N-thio-acetyl compounds derived from naphthylamine, p-iodoaniline, amino-pyridine first converted by condensation with chloro-acetone into N-substituted 2.4-dimethyl-thiazolium salts and by using these compounds in the process instead of 2.4-dimethyl-Nophenyl-thiazolium iodide employed in the above-Q examples, there are obtained dyes that contain various cyclic radicals, substituted or unsubstituted, linked to the nitrogen atom of the heterocyolic ring. 7 v

It will be understood that instead of the symmetrical carbocyaninedyes unsymmetrical dyes may be prepared and it should further be underexamples is not intended to exclude similardyes,

such'as isocyanin'e dyes, merocyanine dyes and polymethine dyes having a longer polymethine chain. Merocya nine dyesina'y be prepared, for example. by refluxing forabout 20 minutes a solution of 496 "grm. 2,4-dimethyl- 3 phenyl thiazolium iodide and .45 grm. diplienyl' formamidine in 5 cos. acetic anhydride, separating the 2-acetanilidovinyl- 3-pheny1-4-methyl thiazolium iodide from the coole'dsolution and condensing the product with rhodanines, pyra'zolones and the like as follows:

A solution of .17 grm. acetanilidovinyl-phenylmethyl thiazoliumiodide and .08 grin. 3- phe'nylrhodanine in 2"cc'sflab'solute 'ethylalc'ohol to-whih about .1 ccfitriethylamine hasbeen added, isrefluxed for about 20' minutes and the'n'lseptffor several hours at a temperatureof ll? The crystals of the dyeform'ed'are washed'iwith ether.

"The 'dye which s believed to be the 3-plienyl-5 (3ephenyl 4-methyl 2-thiazoly1idene-ethylidene) rhodanine has its absorption maximum at about 530 If instead of the phenyl-rhodanine .07 gm. 1 phenyl-3 methy1-pyrazolone-(5) is used a'dye is obtained which is precipitated from the solution by ether and which is washed with ether. The dye which is believedto' be the 3' 1'nethylphenyl-4-(3-phenyl- 4 -methyl 2- thiazolideneethylidene) PYrazolone-(Ei) has its absorption maximum at about 480 The dyes may be incorpor ted in a s'ilverhalide gelatin emulsion by bathingfthe emulsion c'o'ating'inan alcoholic or aqueous alcoholic dye soluti'on. Or the dyes may beincorpo'rat'ed in the emulsion, preferably into the finished emulsion before coating the same on the plate, 'filrn, paper orother support. For example, to a silver bromide-iodide gelatin emulsion which has 'a silver content corresponding to 60 grms. silver nitrate pe ik l emulsion and which has a speed of about 29 Sch. there is added a 1% ethylalcoholic solution of the sensitizing dye. 20 cos. dye solution per kiloemulsion are used. The emulsions are then coated.

A polymethine dye having a polymethine chain including more than three carbonatoms may be prepared by heating for about 5 minutes. .32

grm. 2 4-dimethyl-S-phenyl-thiazolidm iodide with .14 grmi glutaconic dialdehyde dianil'ide and .22 cc. triethylamine in 4 ccs. absolute ethyla cohol, until the solution has become bluegreen. The dye crystallizes from the solution kept at low tem erature for several hours. The novel N-aryl quaternary salts and novel method of making such salts as herein disclosed having been claimed in our application Serial No. 532.694, filed April 25. 1944. now Patent No. 2,495,260, Jan. 24, 1950, no claim is herein made to such salts or such method.

What we claim as our invention and desire to be secured by Letters Patent of the United States is:

1. A dyestuif corresponding with the formula wherein A and B stand for hydrogen, alkyl or the carbon atoms to complete an aromatic ring; R1 stands for an aryl radical;

njstands. foran integer;s e1ected from the group ,.:..consisting of and 1;

stands for an integer selectediromthe group consisting of 0, 1, 2 and 3; Y Ystands for a member selected from the group consisting of hydrogen and alkyl;

W stands for a radical selected from the group consisting of and =0 in whichX stands for an anion; I

R2 stands for a hydrocarbon radical;

Ra stands fora member selected from the group I consisting of hydrocarbon radicals, an atom -c hain including three atoms which serve to --complete a 5-membered hetero ring withvat 2. A thiazolium dye having a phenyl radical directly linked to the quaternary nitrogen atom ofthe thiazolium ring.

' 3.'Athiazolium cyanine dye having an aryl subs'tituent on the N-atom of the thiazole ring. 4, A thiazolium cyanine dye having a phenyl substituent onthe N-atom of the thiazole ring'.'-

j A thiazolium cyarn'ne dye having a halogenated phenyl substituent on the 'N-atom of the hiazql i iin I a 5., A thiazoliumcyanine dye having a chlorophenyl 'substituent on the N-atom of the thiaz'ole ring n J 7. A thiazolylidene merocyanine dye having an 'aryl substituent on the N-atom of the thiazolylidene ring. v 81 A thiazolylidene merocyanine dye having an aryl substituent on the N -atom ofthe thiazolylidene ring, the thiazolylidene radical comprising a simple thiaz'olylidene ring.

9. The cyanine dyesrepresented-by-thefollowy 1 lfp mu a HO?S in which X stands for an anion.

10. The cyanine-dyes represented by thefollowing general formula f:

5 in which X stands for an anion.

11. The cyanine dyes represented by the following general formula:

0H5 r oom x wherein X represents anacid radical. 5

12. The c'yanine dye represented by the following formula: 1

HELLA MICHAELIS, Sole Heir of 'theEsbate of Walter Michaelz's, De-

ceased. 1

No references cited." 

1. A DYESTUFF CORRESPONDING WITH THE FORMULA 